Hi to Dev and Mrtennis,
Dev, the designer of the Concert Fidelity DAC -040, Mr. Tsuda does not believe in using XLR cables. I still use the Stealth Sextet with BNC connections, so I use a high end custom built Cardas BNC to RCA adapter to go into the DAC. I have always used a single ended Stealth Indra IC's from the the DAC to the preamp and still do. I would have never made the move to the CF DAC-040 from the AA Tube Hybrid DAC if it was not on a significant higher level in it's sonic performance and it really is!
Mrtennis, I have heard the Zanden DAC and find it to have what you call a classic tube sound which means to me a beautiful midrange, kinda rolled off high end and a rather mushy bottom end. The CF DAC-040 not only uses 12AU7's but is also tubed rectified, so yes it is tube based. It gives you the natural timbres, 3D imaging, and tonality that tubes have to offer, but is very detailed, transparent, and has excellent extension on the top and bottom unlike other tube based DACS that I have auditioned in the last 3 to 5 years. My second favorite DAC is still the AA Tube Hybrid DAC, this is based only on redbook format which is what I only listen to in my collection of music.